What are differences among Dim, Public and Private statements in VBScript?

Private: When we declare private statement variable than these variable are available only in taht script in which they are declared.
Public: When we declare public statement variable than it will be available for all procedures of all scripts.
Dim: When we declare Dim statement variable at  the script level are available for all procedures of all scripts.Where as at the procedure level variables are available only in procedure.